Scaler Plugin

Plugin BPP_Scaler is designed for scaling and positioning the frame for recording.

By stretching and positioning the frame, plugin allows to remove edge effects not by cutting out the edges with further stretching the picture to original size.

When using plugin you should remember that vertical shifting of interlaced picture by odd number of lines is equivalent to change the order of fields in video stream. The same situation but with the groups of lines instead of the whole picture appears on vertical scaling of the picture. If you feed such video stream through some deinterlace filters you'll see not only jitter on moving scenes but roughly the following picture:

To avoid this, before scaling the interlaced picture it must be processed by deinterlace filter. If you need to preserve interlaced structure of frame, then you need tu turn on setting «Scaling by fields» before positioning and scaling picture by plugin.

Scaling by fields – universal setting and it works similarly with progressive and interlaced video. Nevertheless it may introduce some distortions as a loosing of vertical sharness and doubling of small parts of picture. That's why if you know for sure that the video is progressive, then it is better to turn off this setting. On vertical size less or equal to 288 lines deinterlacing and scaling by fields are turned off automatically.

Taking all that into account, you may use the BPP_Scaler plugin not only for recording but for preview also. However scaling and positioning the picture with the help of hardware accelerator of you display adapter by Behold TV application hasn't the drawbacks mentioned above.